Science fiction action that begins with Boy meeting Gyaru!

Because of a misunderstanding 8 years ago, Jung Da-ae and Lee Han-eol are mortal enemies. To make things worse, their siblings get married making these two in-laws! But then the bride and groom are killed in an unfortunate accident. In a moment of mourning and arguing in the middle of the road, Jung Da-ae and Lee Han-eol are hit by a truck, killed and transported back to when they were in high school! Is this their chance to fix everything?!

From Chibi Manga:

Just when I thought it'd start with you, you disappeared; I would've never thought this...

Yuna has lost trust in love after her first boyfriend Takumi broke up with her. Shiina-kun from her class has already confessed to her twice and now finally she approached onto love another time. But Takumi appears in front of her!! What will the swaying Yuna do!?

A yakuza marriage royale filled with deception begins!

Having received news that the one who manages to marry her will have all of the world in their hands, Ageha, the granddaughter of chief of the Tsukishiro gang, gets targeted by yakuza from all over Japan?!

"I still haven't had my first love though?!"

Although Mio wanted to become good friends with Haihara-kun who transferred to her class. But the first impression she received was the worst ever! But since with her grades, she was in danger of getting retained for a year, she has to go beg Haihara-kun to help tutor her??

Marriage of teacher Ojiro and high schooler Fumino, whose parents have passed away. Includes a total of five stories following their wedding day.

This school is funded by Kagarizuki family. Kagarizuki family has 4 sons and Setsu is the youngest one. Moreover, he's an idol at this school. On the other hand, Misaki Chiyo seems to hate Setsu.

The truth is that Setsu is a vampire, and he always drinks Chiyo's blood. Why does she give her blood to someone she hates? Is there a secret between these two?

From Chibi Manga:

Natsuho visited an abandoned shrine during her high school trip; after the school trip, strange things kept happening to her - like going back in time. What's even more weird is lone wolf Kayano, staring and following her around.

The main character and “anti-hero”, The Rapeman, is a high school teacher by day and dispenses his surreal brand of “justice” at night under the business “Rapeman Services”, which is co-run with his uncle, a former surgeon. He uses rape as his weapon. The business' motto is “Righting wrongs through penetration”.

Clients call on The Rapeman to handle cases such as the revenge of a jilted lover, forming parental bonds through a traumatic crisis, making disruptive co-workers more docile and other things of that nature. When engaged in his night trade, The Rapeman wears a black leather ski mask shaped like the head of a penis but no trousers or underwear. In the middle of a rape, if the woman became unresponsive or appeared to be enjoying the violation, he would use a “special technique” such as “M69 Screwdriver” or “Infinite Loop” to apply more pain to the victim. He sometimes has regrets for the contracts he fulfills, but he always does the job.

In recent years, Japan has become the shining light of Asia, with its noteworthy achievements in the fields of Science and Technology, Medicine and the like.
But while there are a great number of rich and successful Japanese people, there are even more who're engaged in a furious struggle simply to earn their day-to-day living expenses -- all the while battling dangerous and money-consuming addictions such as gambling and alcoholism. What will these people do when they require the cash to feed the never-ending desires that are part and parcel of being human? How miserable and dangerous might their lives become if they fall into traps set by black market money-lenders to ensnare just such weak-willed individuals?

Note: Won the 56th Shogakukan Manga Award for general manga in 2011.

The story of a middle school girl trying to find herself in the confusion of adolescence.
Skateboard-loving Ichiri Sanjou, nicknamed "Icchi," may look like a normal energetic kid, but whenever she sees the full moon, she is hit with a wave of emotion she cannot comprehend.
The series revolves around her learning the Afro-Brazilian martial art of Capoeira.

"Maybe I've been waiting for such a moment for a long time!" While being estranged by his daughter and being blamed by her wife, middle-aged office worker Iwashita lived modestly in his own way. This was his norm at least until he met a girl, Shiina, who suddenly appeared one day in front of him. She approached Iwashita as a 'customer' for "a meal for 20,000 yen". A story of a small escape begins with a painful and dazzling 15-year-old girl seeking her own value and a 40-year-old middle-aged man struggling between reason and desire.

In this world, there are Strays - people who arrived from another world's Japan. These Strays were responsible for a great disaster in the past so upon being spotted, they are meant to be killed by Executioners.

Menou, an Executioner, meets a Stray named Akari, who she kills without hesitation. Yet, Akari comes back to life. Searching for a way to kill her, this journey of Akari and Menou begins.

Mukouda Tsuyoshi was summoned from modern Japan to a different world of sword and magic. He thought of what kind of a huge adventure was waiting for him, but actually, Mukouda is just a civilian who got caught in a "Hero Summoning" by accident!! And that Mukouda's base status is very shabby compared to the legitimate heroes...
The only thing that he could rely on in this world is his unique skill "Net Supermarket," which enables him to order goods from modern Japan, and prepare them for various personas attracted by a different world's food...

*record scratch* *freeze-frame on Haru Koyama getting choked by a horny naked dude* Yep, that’s me. You’re probably wondering how I got into this situation. Not by choice, I can tell you that! It started when my weirdo classmate, Chiba, tried to save me from a runaway truck and got us both killed instead. Idiot. Then we got transported to another world, which I guess is like an otaku dream come true, or something? Chiba ends up with cheat abilities, and what do I get? Nothing! Lucky me, I get to be a sex worker instead. Gotta earn money somehow — but since I have to do it, I’m gonna kick ass at it. This world treats women even worse than the one we came from, so things get…rough. Still, I’ve made friends with some girls, and if I can juggle Chiba’s idiocy and Sumo the virgin’s emotions on top of all the various kinks my customers throw at me, things will be all right…won’t they?

The protagonist, Masaru, has just inherited a big fortune after the death of his father. However, people are trying to get their hands on it by any means necessary, even if it means killing him. Narumi helped Masaru from being kidnapped after fighting some weird guys. He found out that they're not humans but wooden puppets with amazing strength. After a hard fight, Narumi was forced to admit that he's no opponent for them; and just when he started to think that Masaru would be captured, Shirogane, Masaru's watcher arrives from France with a weapon, the puppet Arlequin. Here, begins the story of Karakuri Circus.

You can't leave this island until you've killed 100 people. The most deadly survival game begins on a solitary island where desires swirl and only the strongest survive!

From DrCoke at MangaHelpers:
He has never been the type to stand out in the class. Kurihara Yuzuru has lived life by avoiding entering the lives of others, staying to himself. The story begins where he has to go to a whole new school, which means new classmates. He lacks any confidence to make new friends, so the fear of rejection drives him into a wish he never thought he would make. This single wish leads to a first day of class he would never forget. Yuzuru will have to make choices that will significantly alter others' lives, choices he could never make in the past.

Crow, the loyal butler of a villainess, realizes through a series of chance events that he has in fact been reincarnated into another world.

With a new perspective on life, he realizes just how badly he's been treated by this haughty, egotistical and prideful noble lady he calls his mistress until now, and boils with rage at the injustice.

However, after deciding to take revenge on her in a risque way, he comes to realize that she's a lot easier than she looks...

This is a story of how a reincarnated butler tames his villainous mistress in lustful ways, but ends up making her truly happy.

Shizuku Hoshikawa, a high school girl who lives avoiding contact with people, writes a novel which is accidentally read by her classmate Kaori Asaka.
However, when she reads the novel, she ends up saying: "Let's have a love relationship, for the next job…"